U.S. Pat. No. 4,333,772, assigned to the same assignee as the present application, discloses a fiber waste unloading arrangement for effecting the removal of fiber waste from the collection chambers of a plurality of traveling pneumatic cleaners traveling adjacent respective groups of textile machines by employing a plurality of unloading stations connected to a common source of suction. In the unloading arrangement of said patent, only a single one of the plurality of unloading stations may be actuated at any given time so that it is necessary to provide only a sufficient capacity to provide suction air flow for only a single unloading station, thereby providing a cost savings in both initial expenditure and ongoing energy requirements. However, the motor and fan providing the common source of suction operate continuously, that is, both during the time that a traveling cleaner is being unloaded at one of the unloading stations, as well as during the time between unloading intervals of the traveling cleaners. Since it is usually necessary to unload the fiber waste from the traveling cleaners only one or two times during each eight-hour shift of operation, the continuous operation of the motor and fan providing the common source of suction results in a waste of energy.
Also, the controls of the unloading arrangement disclosed in said patent provide for the unloading of the traveling cleaners in the order in which the traveling cleaners arrive at the respective unloading stations, in what may be termed a "first come, first served" manner. Thus, it is possible for a first traveling cleaner to be in the process of being unloaded at a first unloading station when a second traveling cleaner moves in position at a second unloading station to be unloaded, but this second traveling cleaner will not stop and be unloaded because the first traveling cleaner is being unloaded at the first unloading station. If a third traveling cleaner is being unloaded when the second traveling cleaner again approaches the second unloading station, the unloading of the second traveling cleaner will again be delayed. After the third traveling cleaner is unloaded, if the first traveling cleaner arrives at its respective unloading station before the second traveling cleaner arrives at its unloading station, then the first traveling cleaner would be unloaded again and the second traveling cleaner may again be delayed in being unloaded. Since the unloading of the traveling cleaners can occur only at timed intervals, it is possible that the bypassed second traveling cleaner may not be unloaded during an entire unloading cycle and will become overloaded with waste fibers to the point that it is not possible to completely unload that particular traveling cleaner even during a subsequent unloading cycle.
In the unloading arrangement of U.S. Pat. No. 4,333,772, a timer is provided with each traveling cleaner for providing individual collecting and unloading cycles for each traveling cleaner. Thus, while correlation between the unloading cycles is attempted, the unloading cycle of a certain traveling cleaner may occur at a different time interval than the unloading cycle of one or more of the other traveling cleaners.